Regulation of Singlet and Triplet Excitons in a Single Emission Layer: Efficient Fluorescent/Phosphorescent Hybrid White Organic Light-Emitting Diodes.

ABSTRACT: Two efficient fluorescent molecules, viz., (E)-2-(2-4-(1-2,3-dihydrobenzo[b][1,4]dioxin-5-yl)-4,5-diphenyl-H-imidazole-2-yl)-[1,1-biphenyl]-4-yl)vinyl-1-yl(naphthalene-1-yl)-1H-phenanthro[9,10-d]imidazole (DDIBNPPI) and (E)-4-(2-(2-(-4'-1(2,3-dihyderobenzo[b][1,4]dioxin-5-yl)-4,5-diphenyl-1H-imidazole-2-yl)-[1,1'-biphenyl]-4-yl)vinyl)-1H-phenanthr[9,10-d]imidazole-1-yl)-1-napthronitrile (DDIBPPIN), were designed and synthesized. DDIBNPPI and DDIBPPIN were obtained by rupturing the covalent bond of phenanthrimidazole core to prevent aggregation-induced quenching. In DDIBPPIN, naphthonitrile group was incorporated into azomethine nitrogen of phenanthrimidazole to enhance charge-transfer ability. The DDIBPPIN/CBP:DDIBPPIN-based device shows blue emission with ?c (current efficiency) of 4.91/4.10 cd/A, ?p (power efficiency) of 4.56/3.84 lm/W, and ?ex (external quantum efficiency) of 5.11/5.96%. The ?s (exciton utilization efficiency) values of DDIPNPPI and DDIBPPIN are of 27.0 and 30.3%, respectively. The DDIPNPPI and DDIBPPIN materials employed as a host to fabricate green and red phosphorescent organic light-emitting diodes. The red/white devices (with 0.4% dopant concentration) with DDIBPPIN:Ir(MDQ)2(acac) exhibit maximum L of 69889/26319 cd/m2, ?ex of 19.6/16.6%, ?c of 34.6/35.6 cd/A, and ?p of 35.8/36.6 lm/W. The device with DDIBPPIN:Ir(ppy)3/DDIPNPPI:Ir(ppy)3 exhibits green emission [Commission Internationale de l'Eclairage (0.30,0.60)/(0.30,0.60)] with maximum L of 69906/69482 cd/m2, ?ex of 17.9/17.0%, ?c of 59.8/58.6 cd/A, and ?p of 63.6/61.3 lm/W. The white device using DDIBPPI:Ir(ppy)3 (with 0.4% dopant concentration) exhibits maximum L of 22152 cd/m2, ?ex of 15.8%, ?c of 31.4 cd/A, and ?p of 36.1 lm/W.

SUBMITTER: Jayabharathi J 

PROVIDER: S-EPMC6751706 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature